In lead-acid storage batteries, the art is constantly in search of lead paste or other forms of lead oxide active material which exhibit increased electrochemical usage in the course of battery discharge. Typically, for lead paste comprised of leady litharge in its commercial form, active material utilization in an electrochemical cell only reaches the level of approximately twenty-five percent of the theoretical active material capacity of the electrode. The art has long recognized the relationship between enhanced surface area of the particulate lead oxide of the lead paste and improvements in active material utilization. Thus, the greater the surface area of the particulate lead oxide, the greater is the exposure of active material to electrolyte.
The lead processing art has looked to such techniques as fuming and comminution of lead oxide in providing increased surface area of lead oxide, the latter as disclosed in British Pat. No. 474,267 (1937).
Various prior art efforts have involved chemical treatment of lead oxide to produce lead dioxide. Such efforts, not related to surface area considerations are discussed in detail in the prior art statement filed herein pursuant to 37 C.F.R. 1.97 and 1.98. They have encompassed treatment of insoluble lead salt in the presence of alkali with halogen or hypohalite and the treatment of lead oxide in aqueous alkali solution under pressure of air or oxygen. In the above-noted British patent, disclosure is made of a method for providing oxides and sub-oxides of lead by subjecting a finely divided dry solid to ozone. The practice is affected particularly by forced circulation of ozone through an airborne suspension of dry material, or by bleaching treatment of the dry solid by application of ultra violet light thereto. Comminution is completed prior to ozonation in this practice, whereby the material is in its finely divided form prior to oxidation by ozonation. In applicant's view, such prior art efforts providing lead dioxide by chemical oxidation of lead oxides would be of benefit in facilitating so-called electrochemical formation of electrodes having lead oxide active material, by reason of lead dioxide enhancement of electrical conductivity of such active material. Thus, prior chemical oxidation practice would enhance customary practice wherein lead oxide active material is rendered electrically conductive by conversion to lead dioxide in the course of initial electrolysis thereof, i.e., in initial battery charging. Nonetheless, no practice is presently known which would suggest achievement of both such enhancement of electrical conductivity and increase of lead oxide surface area jointly by chemical agency.